Articles of Ignition Resistant Cotton Fibers

ABSTRACT

A bi-regional fiber with a cellulosic core and a wax outer sheath is disclosed. The sheath can comprise high melting temperature wax. The fiber may be produced by processing the natural fiber at temperatures less than 70° C. The fiber can be processed in a standard manner such as, for example, a Keir process which may include bleach at approximately 100° C. with a wax subsequently added at a temperature sufficient to disperse the wax over the fiber surface. The fibers are ignition resistant as measured by industry standard tests. The wax may comprise from about 0.4 to 25 percent or greater of the fiber by weight. The wax may be natural wax, synthetic or emulsified wax or blends thereof. The bi-regional fibers can be blended with other fibers including BRCF fibers to create fire resistant fabrics including clothing, blankets and household materials.

REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.14/071,432 entitled “Novel Ignition Resistant Cotton Fiber, Articlesmade from Ignition Resistant Cotton Fibers and Methods of Manufacture”filed Nov. 4, 2013, which is entirely incorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention is directed to ignition resistant and/or flameretardant whole cotton fibers, and whole cotton fibers having a bleachedcellulose region at the core and an outer region comprised a wax sheathor surface. In particular, the invention is also directed to methods forthe manufacture of the ignition resistant whole cotton fiber, and toarticles made from a multiplicity of said whole cotton fibers.

2. Description of the Background

Cotton is a natural fiber and is renewable. That is, a new crop can begrown each year. Most synthetic fibers are made from petroleum which isnot a renewable resource. Cotton has been known for thousands of years,and accordingly, the physical and chemical properties about cotton arewell known. Because of a unique chemical nature, cotton can be made tobe fire retardant, have wash-wear qualities, and be wrinkle free, amongother properties. Cotton also can be blended with other textile fibersto enhance the overall performance of the blended fabric.

According to Cotton Inc., the US produced 15.5 million bales of shortstaple cotton and 583,000 bales of long staple cotton in 2014. Each baleweighs 480 pounds. This represents only a small fraction of the worldcotton production. This converts to 5.56 million metric tons of shortstaple cotton and 140,000 metric tons of long staple cotton produced inthe USA. The State of Texas is the largest producer accounting for 40percent of this crop followed by Georgia, Mississippi, North Carolina,Arkansas and Alabama.

Raw cotton, in other words the unprocessed material obtained fromplants, like all vegetable matter contains minerals, resins, gums,protein, tannins, oils and waxes and carbohydrates in addition tocellulose. Cotton normally has to be purified to remove these productsfrom the primary cellulose polymer substrate. Natural cotton istypically bleached in either the yarn form or the fabric form. Thisinvolves boiling the cotton for 30 plus minutes in a strong alkalinesolution. This process cleanses the cellulosic part of the cotton andremoves the natural wax on the outside of the cotton.

Most of the unwanted portions of the cotton plant material are removedin a “Kier” boil process. This has become the standard treatment processin which caustic soda (NaOH) and other processing aids are employed attemperatures of up to 100° C. to solubilize and remove impurities. Theoils and waxes are saponifiable and removed by this preparation process.Continuous processes have been developed which utilize a steam treatment(100° C.) to speed up the process and reduce the time required by theKier (batch) method. A comparison of the composition of raw cottonversus a Kier like treatment is shown in Table 1.

TABLE 1 Percent Composition of Cotton: Raw vs. a Kier* Treatment RawCotton KIER Cellulose 80-85 99.1-99.5 Wax 0.4-1.0 0.01-0.15 Ash 0.8-1.8 0.05-0.075 Pectin's 0.4-1.1 Nil Protein (Nitrogen) 1.2-2.5 0.05-0.10Pigment, Resin 3-5 Nil Moisture 6-8 Nil *(Mathews' Textile Fibers,5^(th) ed. Wiley & Sons, NY, 1947 p, 100)

Virtually all impurities are removed by Kier boil treatment. Color isremoved by a subsequent bleaching process normally employing eitherperoxide or hypochlorite process which removes the color to the desireddegree of whiteness. Following these treatments, the cotton fabric isready for numerous after-treatment processes such as dyeing by any of avariety of methods, conversion to a wash-wear, conversion to flameand/or ignition resistance and/or other treatments, includingcombinations of all of the above. Further treatments to enhance theutility of treated cotton fabric or cotton fabric blends are known.

The wax in the cotton fiber is not one having a single component, but isthought to have a blend of complex esters, acids and alcohols. The waxesare thought to have a composition involving C₂₄-C₃₄ primary alcohols aswell as other complex mixtures and a melting point of about 77° C., adensity of 0.976, an acid value of 29, saponification value of 57 (afteracetylation, 137), an acetyl value of 84, an iodine number of 27, and68% of un-saponifiable material (having an acetyl value of123—indicating an absence of wax esters and a large proportion of freewax alcohols). It is probably the free wax alcohols that survive thetreatment conditions outlined in the Kier and like processes. Thepurpose of the wax in the fiber is to protect the cotton seed from theharsh environments it may be subjected to prior to spring planting.Loose raw cotton will float on water for months; hence the cotton seedis protected against winter rains damage. Still, it is these waxcomponents that survive the processing treatments which results in thesurprise benefits of ignition resistance cotton.

To reduce the inherent flammability of cotton fabrics, cotton fiber canbe combined with flame and/or ignition resistant fibers, such assynthetic fibers. For apparel use modacrylic fibers and matrix fibers ofvinyl/vinyon, among others, have been used. The resulting fabricsfrequently lack the performance properties and consumer appeal of purecotton fabric. Fiber composed of 50 percent vinal and 50 percent vinyon,for example, is not strong enough to form its own fabric and is noteasily dyed. Another disadvantage of this method of producing fireresistant fabric is that yarns containing two or more fibers withdifferent flammability characteristics which tends to produce fabricshaving non-uniform cross-sectional areas, and therefore, non-uniformfire resistant characteristics.

Alternatively, cotton fabric can be treated with flame retardantchemicals and/or chemicals that promote ignition resistance that changeor interrupt the burning process known as pyrolysis. However, cottonfabric treated with such chemicals lack the performance properties andconsumer appeal of pure cotton fabric. Most of these treatments involveharsh chemicals which are very unfriendly to the environment. Severalhave also been linked to health problems in infants and newborns. Forthis reason most of the newborn and infant bedding and sleepwear hasbeen switched to 100 percent polyester.

During pyrolysis most textile materials must first undergo decompositionto form volatile combustibles before they will burn. Decompositionoccurs when the textile material is exposed to a sufficient source ofheat. The decomposition temperature for textile materials is dependentupon the composition of the material and is different for differentfibers. When the textile material decomposes, volatile materials areformed. The volatile materials ignite in the presence of oxygen toproduce heat. The heat produced during pyrolysis may cause furtherdecomposition of the textile material leading to its completedestruction.

The application of flame retardant chemicals or chemicals that provideignition resistance interrupt pyrolysis. For example, the flameretardant or ignition resistance may be converted upon heating intoacids and bases that catalyze decomposition of the textile at lowertemperatures than are required for the formation of volatilecombustibles. Compounds containing phosphorus are converted to acidicmaterials that catalyze the thermal decomposition of the polymer.Alternatively, the flame retardant or ignition resistance chemicals maydecompose or sublime upon heating to release large amounts ofnonflammable vapors which exclude oxygen from the flame.

A need exists for a cotton fiber that is inherently flame and/orignition resistant such that fabric made from these fiber complies withflammability and safety regulations without application of harshchemicals, or with application of reduced amounts of chemical comparedto fabric made from untreated cotton fibers.

A need also exists for a cotton fiber that is made inherently flameand/or ignition resistance such that fabric made from these fiberscomplies with flammability safety regulations by having a ignitionresistant wax sheath without application of flame retardant chemicals,or with application of reduced amounts of such chemical compared tofabric made from untreated cotton fiber.

SUMMARY OF THE INVENTION

The present invention comprises a major departure from the present stateof the art by discovering that bi-regional cotton fiber which has a waxsheath unexpectedly has flame retardant and/or ignition resistantproperties, even after being dyed under low temperature and alkalineconditions.

One embodiment of the invention is directed to bi-regional cotton fibercomprised of a cellulosic center and an outer surface comprised of awax. Preferably the bi-regional fiber is bleached and preferablybleached with chlorine, ozone, peroxide, hypochlorite or a combinationthereof. Preferably the wax comprises at least 0.4 percent by weight ofsaid fiber, more preferably the wax comprises from about 0.4 percent toabout 25 percent by weight of said fiber, and more preferably from about14 percent to about 16 percent by weight of said fiber. Preferably thewax comprises is a natural wax, a synthetic wax, an emulsified wax or amixture thereof, wherein the natural wax is preferably a cotton wax, ajojoba wax, a soy wax, a carnauba wax, or a combination thereof, andalso preferably the wax has a melting point temperature of about 70° C.or greater or about 90° C. or greater. Preferably the fibers have atleast 10 percent greater tensile strength as compared to natural cottonfibers, and more preferably at least 20 percent greater tensile strengthas compared to natural cotton fibers. Also preferably the bi-regionalfibers further comprise a saponified acid or derivative thereof on theouter surface of the fiber. Preferably the saponified acid or derivativethereof comprises lauric acid, myristic acid, palmitic acid, stearicacid, oleic acid or combinations thereof. Preferably the bi-regionalfiber is fire retardant and/or ignition resistant and/or meets orexceeds a vertical burn test conducted according to FAR 25.853(b).Preferably, the fire retardant and/or ignition resistant bi-regionalfiber contains no harmful chemicals such as organohalogens. Alsopreferably, the bi-regional fiber has reduced water absorption ascompared to a natural cotton fiber.

Another embodiment of the invention is directed to materials comprisedof a plurality of the bi-regional fibers of the invention. Preferablythe materials are fire retardant and/or ignition resistant and, alsopreferably, the materials have reduced water absorption as compared to anatural cotton fiber. Preferably the materials have a wrinkle resistancegreater than conventional cotton.

Another embodiment of the invention comprises fibers and/or materials ofthe invention further comprising additional fibers such as, for example,natural fibers, synthetic fibers, carbonaceous fibers, and combinationsthereof. Preferably the synthetic fibers comprise polyester and thecarbonaceous fibers comprise flexible bi-regional carbonaceous fibers.Also preferably, the synthetic fibers comprise about 50 to about 90percent polyester and about 10 to about 50 percent bi-regional fibers.

Another embodiment of the invention comprises apparel comprised ofmaterials and/or fibers of the invention as for infants, toddlers,children and adults. Preferably the apparel comprises shirts, socks,pants, sweaters, hats, coats, undergarments, sportswear, skirts, sweats,scarves, gators, dresses, tops, blankets, and designs and combinationsthereof. Also preferably, the apparel is suitable for wear inenvironments wherein conditions are greater than and/or less than bodytemperature including for sports activities such as for example, snowsports, hiking in mountains, jungles and deserts, and rock and mountainclimbing. At least in part due to immediate transfer of water and watervapor through the material, apparel of the invention is suitable forwear in both ambient and extremes of temperature environments.

Another embodiment of the invention comprises methods for manufacture ofa fiber comprising: bleaching a cotton fiber; and applying a wax to thefiber and, also preferably, no wash step is performed after bleachingand before application of the wax. Preferably bleaching comprisestreating the fiber with chlorine, ozone, peroxide, hypochlorite or acombination thereof and, also preferably, bleaching is performed atabout 40° C. or less, or at room or ambient temperature and at a pH ofbetween about 6 and about 8. Preferably the fibers comprise ignitionresistance without added harmful chemicals. Preferably the manufacturingcombines fibers of the invention with polyester fibers and alsopreferably, the polyester fibers are treated with a solution of ahydrolyzed partial condensation of trimethoxy methyl silane.

Other embodiments and advantages of the invention are set forth in partin the description, which follows, and in part, may be obvious from thisdescription, or may be learned from the practice of the invention.

DESCRIPTION OF THE INVENTION

Cotton fabric can be made flame retardant or ignition resistant bytreating with certain chemicals that change or interrupt pyrolysis(e.g., organohalogens, compounds containing bromine or chlorine). Thesetreatments typically involve harsh chemicals which are unfriendly to theenvironment and linked to health problems. Many of these compounds areknown to be harmful and may be carcinogenic and/or toxic. In addition,cotton fabrics so treated lack the performance properties and consumerappeal of pure cotton.

It has been surprisingly discovered that cotton fibers can be made fireretardant and/or ignition resistant without the need for harsh orharmful chemical treatments by creating hi-regional fibers of theinvention. These bi-regional fibers of the invention preferably containsubstantially reduced or no harsh and/or harmful chemicals. Bi-regionalcotton fibers of the invention are made from regular, ecru (i.e., raw)or unbleached cotton either in the yarn or in fabric form. The resultantbi-regional cotton that preferable has at least about a ten percent ormore greater tensile strength as compared to untreated or conventionallytreated cotton fibers, more preferable about 20 percent or greater, morepreferably about 30 percent or greater, more preferably about 50 percentor greater. Fibers of the invention with increased tensile strength ascompared to regular process cotton using high temperature and highalkalinity, also have surprisingly superior moisture handlingcapabilities and wrinkle resistance as compared to traditional cotton.Superior moisture handling capability means that the fiber or fiberassembly is less absorbent of water.

Bi-regional cotton fibers of the invention are preferably ignitionresistant and flame retardant and pass the 45 degree angle flameimpingement test as prescribed for children sleepwear in the UnitedStates. The bi-regional cotton has no harsh chemicals in contact withthe infant skin and requires no additional ignition resistance or flameretardant treatment such as that required by traditional cotton. Thechemical treatments conventionally required for flame and ignitionresistance normally used in traditional cotton have been linked tosudden infant death syndrome and low IQs. Further, the cost of makingthe bi-regional cotton is competitive with polyester and should restorethis material as the material of choice for newborn, infant andchildren's clothing.

The preferred embodiment of bi-regional cotton retains the natural waxesand oils of raw cotton and requires no additional finishes or lubricantsand has superior handling compared with traditional cotton fabrics. Thebi-regional cotton dyes in a more uniform manner than traditionalprocessed cotton, such as the Kier process, and has far superior comfortproperties.

The intended consequence of the Kier process, which is the standardprocessing of cotton, is that it removes all of the wax from the cottonfibers. A low alkaline and low temperature process has been developedthat does not remove the waxes. It was surprisingly discovered that anunexpected result of such a treatment allows the wax to either migrateto the surface of the cotton fiber or does not remove the surface waxthereby markedly increasing the ignition resistance of the final cottonfabric. Also the method with mild heating migrates the wax to thesurface forming the bi-regional fiber. Other properties such as anenhanced hand feel and smoothness of the fiber assemblies, is alsoobtained. The process requires that all treatments must be performed ata low temperature and alkalinity so as not to result in unintendedsaponification which could solubilize and result in removal of the wax.

Dye-ability is an important asset for any textile fiber. Cotton isfortunate that it can be colored by numerous different dyeing classes.Unfortunately, many of these such as vat, sulfur and/or naphthol, areperformed employing high alkaline conditions. The choice of dye classvaries in the fastness properties they are able to impart to thefinished dyed cotton such as light fastness, wash fastness, fastness toperspiration and the like. To achieve uniformity of dyeing, the cottonis first prepared so that a uniform uptake and leveling of the applieddyestuff is achieved. The normal preparation step involves a Kier typetreatment followed by bleaching to remove natural colored impurities.The most desirable dyeing conditions which insure survivability of theresidual wax is a low temperature/low alkali reactive dyeing process.

Accordingly, the normally employed Kier/bleach process can be replacedwith either a low temperature-peroxide/catalyst or low alkalinityhypochlorite process. These bleaching steps employ an oxidative ratherthan a high heat/alkalinity process to remove cotton impurities. Theresult is a process that retains essentially all of the waxy compositionof the cotton fiber. In addition, the wax appears un-expectantly toeither migrate to the surface of the fiber or remain on the surface andis not removed by these oxidative processes. This process creates a waxlayer on the outer surface of the cotton, thereby causing fibers to bebi-regional. This surface wax contributes to improving the ignitionresistance of the fabric.

When using peroxide bleaching, the bleach temperature preferably doesnot exceed 60° C. Normal peroxide processes are done at the boil oremploy a steaming step, for example, by saturated steam at 100° C. orgreater for continuous operations. Instead of employing a highalkalinity to stabilize the peroxide bath, only a 2 g/l caustic solutionis employed along with a complex blend of low foaming surfactants, astabilizer (e.g., Crosprep HES), and a catalyst that is active at thelower temperature (e.g., Crosprep CAT) is employed. Any remainingperoxide is neutralized employing a non alkaline agent (e.g., CroszymePEK). Crosprep and Croszyme can be obtained commercially fromEurodye-CTC S.A., Jodoigne, Belgium.

If chlorine bleach is used, preferably 1 g/l Cl₂ is employed in thebleach bath to prevent over bleaching and pH is maintained at 7.5 to8.0. Preferably sodium carbonate is used as buffering the bleach bathinstead of caustic soda. This reduces the potential saponification ofthe wax. At lower pH, the bleaching action increases. For cotton fabricswith high natural color content, the temperature can also be increased,but should preferably not exceed 40° C. Preferably the temperature is40° C. or below, more preferably 30° C. or below, more preferably 25° C.or below, and more preferably at about ambient or room temperature. Insuch cases it is preferred to employ the weaker (1 g/l Cl₂) bleachsolution at a higher temperature than to use stronger bleach solutionsat lower temperatures. This is because the activity of the OCl⁻ionresponsible for the bleaching is temperature dependent (see, R. H.Peters, Textile Chemistry Vol. II, Elsevier, New York 1967). NormalChlorine bleaching processes, pads the bleach solution onto wet goodssuch as fabric directly from the kier process. In the process of theinvention, the bleach is applied directly to the dry cloth and problemsassociated with bleaching uniformity in the fabric are reduced. Thebleach solution can be applied by any of the application processes suchas, for example, spraying, foaming, padding or the like.

Acidic products are produced as the oxidation process proceeds whichreduce the normal alkalinity present. Ordinary bleaching with chlorinerequires additional alkali to insure neutralization of the HCl which isformed during bleaching. This results in excessive alkali being presentafter bleaching which is removed usually by a post treatment with aceticacid. Another advantage of this bi-regional cotton process is that anacetic acid wash step, to remove residual alkali, can usually be omittedsince very little residual base should be present after the bleachingprocess. This saves processing time and also expense. The pH of thefabric will be sufficiently low after rinsing so as not to interferewith subsequent dyeing processes.

In a continuous process, J boxes can be employed to store the paddedcloth but the dwell time preferably does not exceed 20 minutes. As withany chlorine bleach methods any residual chlorine is preferablyneutralized with either sodium thiosulfate or sodium bisulfiteantichlor.

Bleaching with bromine is faster than with chlorine but generally themethod is not as cost effective as with chlorine. Small amounts (e.g.,1-2 percent of bromine on weight of chlorine content) added to thechlorine bleach solutions also measurably improves bleaching efficiency(see, R. H. Peters, Textile Chemistry, Vol II, Elsevier, New York,1967).

Other cellulosic fibers that do not have a natural wax content similarto bi-regional cotton of the invention are preferably treated with atopical wax and receive the same or similar ignition resistance. Theseother cellulosic fibers include the Rayon's, Linen, althoughnon-prepared Linen has a natural wax content of 0.5-2.0 percent (havinga melting point of about 62° C.) as well as blends. In these cases it ispossible to subsequently treat the cellulose containing fabrics with anumber of natural wax emulsions. The temperatures of drying will allowthe emulsified wax to evenly distribute itself and become affixed on thefiber surface to achieve the bi-regional structure and the same ignitionresistance as the so treated cotton.

This technique can also be employed to treat cotton fabrics processed inthe classical fashion such as, for example, by the Kier process whichremoves virtually all natural wax. A number of high melting petroleumbased waxes are also known and are available that will also have utilityas substitutes for the natural waxes. Preferred waxes include, but arenot limited to carnauba, bees wax, palm, soy, candelilla, jojoba, woolwaxes, and the like and combinations thereof (see Table 2). Blends ofnatural waxes and petroleum based waxes may also be utilized. Cottonhaving different processing histories can be treated with these types ofwax blends and are included within the scope of the invention.

TABLE 2 Melting Points of Some Natural Waxes (° C.) Bees Wax 62-65 Palm58-60 Carnauba 81-86 Candelilla 68-73 Soy (high melting type) ~82 Jojoba(high melting type) ~70 Cotton ~77

In addition, blends of cellulosic fibers will benefit from a postapplication of an emulsified wax or combination of waxes. Theapplication of the saponified acid derivatives such as, for example,lauric, myristic, palmitic, stearic, oleic and combinations thereofprovide ignition resistance to treated fabrics. These products areremovable in a conventional laundry cycle, but are preferably useful forfabrics that are not intended to be laundered.

Once the fabric has been bleached it is preferably dyed. The dyeingmethod of choice is with reactive dyes that can be dyed at temperaturesnot exceeding 60° C. and at low alkalinity. The dyes form a covalent dyewith active hydrogen on the cotton fiber. The dye is preferably saltedon with high concentrations of sodium chloride. The amount employeddepends upon the dye level required to produce the required shade. Table3 provides levels of salt to employ and concentration of alkali. Apreferred alkali is soda ash and can be employed to achieve the fixationof the dye. Once the dye reaches the desired equilibrium, for examplethe proper shade, 2 gpl soda ash is added to fix the dye within thefibers. This level of alkalinity does not result in saponification ofthe surface wax. Dyeing is continued at the 60° C. until fixation isassured.

TABLE 3 Salt and Alkali Concentrations at Specific Dye Add-ons PercentDye on Fabric NaCl (gpl) Soda Ash (gpl) <0.50 20 10 0.50-1.0  35 151.0-2.0 50 20 2.0-4.0 60 20 >4.0 80 20

One disadvantage of cotton fabric is that the material ignites easilyand burns rapidly. The flammability of a fabric is dependent upon itscomposition (see, Mehta, R. D., Textile Research Journal 44(10): 825-826(1974)). The extent of flame and glow resistance of a fabric increasesas the carboxyl and metal contents of the fabric increased. In view ofthe danger posed by flammable textiles in general, the government haspromulgated consumer safety regulations for textiles including safetystandards for carpets and rugs, mattresses and children's sleepwear. Theflammability characteristics of textiles used to manufacture upholsteryfound in motor vehicles and airplanes are also regulated.

In one embodiment, the invention comprises a bi-regional cotton fiber,fiber assembly or fabric. The cotton or cellulose (e.g., cellulosic)core fiber comprises the fiber core at least 70 percent of the fiber byweight and have a wax sheath or coating (also referred to as the outercore) comprising at least 2/10 of a percent to 25 percent of the wholecotton fiber by weight. The wax coating may be high temperature (highmelting point) wax which is preferably a melting point at or above 70°C. Alternatively, the wax coating may be of lower temperature meltingwax. This bi-regional fiber contains a unique blend of cellulose withwax. The wax may be a naturally occurring wax from the processed cottonball or it may be an emulsified wax added to the fiber surface. This waxcan be added to the fibers after a low temperature processing,preferably less than 70° C. In another embodiment, the wax may be coatedon the fibers after standard process such as, for example, Kierprocessing.

In one embodiment the wax may constitute about 0.4 to 1 percent byweight of the cotton fiber. In another embodiment the wax may constituteabout 10 to 25 percent by weight of the cotton fiber. In anotherembodiment, the wax may comprise about 14 to 16 percent of the cottonfiber by weight.

The fibers or woven fabric made from such fibers become an ignitionresistant fiber. This is attributed to the high wax content of thefibers coating the exterior (see Example 4). The fibers or fabricpreferably exhibit a smooth, silky texture and enhanced moisture (waterwetting) resistance as a result of the wax coating. Fiber of theinvention is preferably stronger than standard cotton fibers because ofthe milder processing conditions employed, such as, for example, lowerprocessing temperature. The cotton of the invention preferably possessesflame resistance (flame retardant and/or ignition resistance) to meetflammability safety regulation without application chemical additives orwith application of reduced amounts of flame resistant chemicals.

It has also been surprisingly discovered that blends of the cotton fiberof the invention can be made with flexible bi-regional carbonaceousfibers (BRCF) as described in U.S. Pat. No. 5,700,573. Blends comprisingpreferably from 10 to 90 percent of the cotton fibers of the inventionwith the balance of the fibers being BRCF. Preferably untreatedcellulose core fiber comprises at least 70 percent of the fiber byweight and the wax sheath comprises from at least 0.2 percent to 15percent of the cotton fiber by weight. These blends are made intoknitted fabrics having densities ranging preferably from 3 to 15 ouncesper square yard are ignition resistant and have superior coolingproperties due to the micro evaporative cooling nature of both thecotton fibers of the invention and the BRCF The ignition resistance ofthe fabric blends, utilizing the BRCF and/or the cotton fibers of theinvention, are determined following the test procedure set forth in 14C.F.R. §25.853(b). Samples preferably pass an FR test and exhibitsuperior thermal resistance values with clo thermal resistance valuesranging from 2.6 to 3.6.

The low-energy room temperature method of cleaning and bleaching leavesthe natural wax sheath around the cotton resulting in significant energysavings and carbon dioxide emission reductions, in comparison to thetraditional high pH effluent process. For each metric ton of cotton, theprocess of the invention produces smarter cotton which reduces CO₂emissions by 560 pounds and reduces energy consumption by 906 kWh. Whenthis process is widely adopted in the USA, CO₂ emissions can be reducedby up 4.43 MM tons and up to 14 GWh. Besides the significant positiveenvironmental impact, the superior smarter cotton is up to 30 percentstronger, shows inherent reduced ignitability, enhanced moisturewicking, stain and easy care properties. Clothing and articles made fromthe smarter cotton are environmentally green and made from a sustainablematerial compared to synthetic materials. For example, 5.7 millionmetric tons of cotton will save 906 kWh (kilowatt hours) and 506 lbs.per metric ton. Two forms of smarter cotton are released to the market.

One form of the smarter cotton of the invention that comprises premiumlong staple combed cotton is referred to herein as NuGard. NuGard is aform of cotton fibers of the invention that has significantly improvedproperties compared to conventional forms of cotton. NuGard maximizesthe wearer's comfort in addition to reduced ignitability without addingflame resistant chemicals. Articles composed of NuGard are extremelycool in warm weather, have a naturally ultimate soft silky hand, andshow reduced tendency to staining and wrinkling as compared withconventionally treated cotton and polyester. Sweat rings with Nugard arenot present thanks to its micro-evaporation power. The natural waxrepels instant spills, facilitates vapor transport inside-out keepingthe wearer cool and dry to the skin. Instead of compromisingperformances, the sustainable lower energy process is in synergy withenhanced comfort, quick dry laundry and easy care conditions.Bi-regional cotton fibers of the invention including Nugard cotton canbe made into most any apparel including apparel for infants, toddlers,children and adults such as, for example, shirts, socks, pants,sweaters, hats, scarves, gators, sweats, coats, undergarments,sportswear, skirts, dresses, tops, and blankets. Other embodiments ofthe invention comprise materials composed of fibers of the inventioncombined with additional fibers and other materials, such as, forexample, leathers, metals, plastics and other polymers in creating mostany design and style of clothing and apparel. Workhorse cotton fabricproducts such as underwear, denim jeans, sheeting, bedding, children'sclothing, and the like can be referred to as DuraGard products.

Treated cotton, because of the wax coated surfaces has the followingpreferred characteristics: (i) increased staining resistance andimproved soil release characteristics; (ii) natural softness and hand;(iii) natural water repellency providing greater dry sleeping comfort;(iv) when blended with diamondown will provide superior thermal comfortby blocking 91 percent of radiant heat loss; (v) enhanced fabric wickability; and (vi) less problems associated with dyeing. Fabricsmanufactured employing the so treated cotton will experience a greaterdegree of polymerization (DP) in the final fabric because of the lessharsh preparation and process treatments normally employed. As aconsequence, in a comparison of water-repelling cotton of one embodimentof the invention shows water beading on and not within the fabric,whereas traditional cotton shows water being absorbed by the fabric.Also because of the lower processing damage, the fabrics possessincreased tenacity (about 14 percent) and elongations (about 14percent). In addition, the milder processing reduces the associatedenergy costs (about 20 percent minimum) as well as lower waterconsumption and waste water treatment requirements. There is also alowering of the CO₂ emissions (about 17 percent minimum) because theprocesses are preferably accomplished at lower temperatures.

Forms of the invention herein shown and described are to be taken as thepresently preferred embodiments. Various changes may be made in theshape, size and arrangement of components or adjustments made in thesteps of the method without departing from the scope of this invention.For example, equivalent elements may be substituted for thoseillustrated and described herein and certain features of the inventionmaybe utilized independently of the use of other features, all as wouldbe apparent to one skilled in the art after having the benefit of thisdescription of the invention.

The term “ignition resistant” as used herein refers to fibers or fiberassemblies that satisfactorily pass the (a) FAR 25.853(b) Flammabilityof Aircraft Seat Cushions, or (b) flammability test or the 45 degreeangle flame impingement test (16 CFR 1610, Standard for the Flammabilityof Clothing Textiles).

The term “fiber assembly” used herein applies to a multiplicity offibers that are in the form of a yarn, a wool like fluff, batt, mat, webor felt, and comprising a formed sheet, screen or panel, a braided,knitted or woven cloth or fabric, or the like.

The term “cohesion” or “cohesiveness” used herein, applies to the forcewhich holds fibers together, especially during yarn manufacture and is afunction of the type and amount of lubricant used, the fiber crimp andtwist.

The term “Kier process” as used herein refers to the prior art standardprocessing of treating raw cotton by boiling the cotton to remove oilsand waxes by saponification from the primary cellulose polymersubstrate.

The term “high temperature high alkalinity processed cotton” meanscotton processed by the Kier process or similar processes conducted attemperatures of near 100° C.

All percentages disclosed herein are “percent by weight” unlessotherwise specified.

The following examples illustrate embodiments of the invention, butshould not be viewed as limiting the scope of the invention.

Example 1 Bleaching with Peroxide

To the cotton fabric is added a solution containing 3-4 gpl, peroxide(50%), 2 gpl caustic soda (NaOH), and 1 gpl of a low foamingsurfactant/stabilizer (such as Crosprep HES) at a 10/1 fabric to liquorratio. The fabric and solution is heated to 60° C. over 15 minutes. Onegpl of a catalyst suitable for low temperature peroxide bleaching (suchas Crosprep CAT) is added and the fabric heated in this mixture at the60° C. temperature for 45 minutes followed by draining and refilling.Acetic acid is added over 5 minutes until the pH stabilizes to 6.5-7.0.The fabric is then treated for 10 minutes with a stabilized liquidcatalase (such as Croszyme PEK) to neutralize any residual peroxide. Thefabric is rinsed, drained and dried.

Cotton yarns can be bleached effectively in a pressure dyeing machine.The pH of the bleach liquors can be easily adjusted to control the pHwith soda ash. The bleach solution is automatically programmed to givealternate inside out and outside in of the yarn package in to insurebleach uniformity. The acetic acid rinse can be controlled to keep thecloth near neutral. This is followed by treatment with the catalase toremove residual peroxide and a final rinse.

Bleaching with Oxygen

The advantages of employing package dyeing equipment for the novel lowtemperature, low alkali bleaching system is essentially the same as thatcited for the chlorine bleach systems via a finishing plant operation.During this dyeing process, pH control is maintained for the bleachsystem. The pH is continuously monitored through the add system of thepackage dyeing machine.

Bleaching with Chlorine

The fabric is padded to 100 percent wet pick up in a solution containing0.2 g/l wetting agent and 1 gpl chlorine bleach at a pH of 7.5-8.0 andstored in a J Box for 20 minutes at room temperature. For highlydiscolored fabrics the temperature may be increased but may not exceed40° C. For pH adjustments, soda ash is preferred because of itsbuffering effect and so the cloth will not need an acetic acid rinse toobtain a final pH of 6.8-7.2. An antichlor treatment with sodiumbisulfite or sodium thiosulfate to remove any unreacted chlorinecompletes the bleaching process.

Fibers derived from raw cotton fiber (ecru) are bleached at less than70° C., preferably at ambient or room temperature, with a bleachingsolution comprising an OX⁻ system, where X is a halogen and where the pHis 6.5 to 8.

Dyeing

The dye bath is set with the proper concentration of dye on the fabric,1 gpl of antifoam such as Croscolor SLR New, 1 gpl of Croscour HP-JS andthe salt concentration from Table 3. The temperature is raised to 60° C.and dye for 20 minutes. Soda ash (see Table 3) is added and dyeingcontinued for 40 additional minutes. The bath is dropped and the fabricis given a hot (60° C.) rinse containing 1 gpl acetic acid. The bath isdropped and the fabric soaped 10 minutes at 60° C. with 1 gpl CroscolorBCSR followed by a hot (60° C.) rinse for 10 minutes and a cold rinse(20° C.) for 10 minutes. Treatment of cellulose containing fabricscontinues after a standard preparation treatment.

Another method of chlorine bleaching is to employ package dyeingequipment. This method offers considerable advantages over continuousbleaching in a finishing plant. The pH of the process is continuouslymonitored via the add tank and corrections can be made while running.After the antichlor treatment the yarn packages do not need to be driedbut the dyeing operation can be started immediately. This bleach methodcan be employed on small runs in order to make and test product changes,for example, in the color line or for product modifications. Further,this method provides better shrinkage control of the yarns since normalshrinkage will have occurred during the package bleaching/dyeingprocess.

Example 2

A desized and bleached cotton print cloth (Testfabrics style 400weighing 3.03 osy (oz/yd²)) was treated at 100 percent wet pickup with asolution of a 0.75 percent owf (on weight of fabric) emulsifiedcandelilla wax, and 0.1 percent nonionic wetting agent. After drying,the fabric passed the 45° C. flammability test, (16 C.F.R. §1610,standard for the flammability of clothing textiles) and did not igniteeven after a 4 second flame impingement.

Example 3

An army carded cotton sateen which had been desized and bleached(Testfabrics style 428 weighing 6.93 osy, and a bleached, mercerized,and carded cotton broad cloth (Testfabrics' style 453, weighing 3.53osy) and a cotton sheeting (Testfabrics' style 493, weighing 4.45 osy)gave the same results (passed the 45° C. flammability test) aftertreating in the fabrics in the manner described above, (treated at 100percent wet pickup with a solution of a 0.75 percent owf (on weight offabric) emulsified candelilla wax, and 0.1 percent nonionic wettingagent).

Example 4

A spun Viscose challis (ISO-105/F02, Testfabrics style 266, weighing4.07 osy) treated as above, did not ignite even after a four secondflame impingement.

Example 5

A Cotton/Linen 56/44 blended fabric (Testfabrics' style L5040, weighing6.4 osy) treated as above did not ignite even after a 4 second flameimpingement. The same results were obtained when bees wax wassubstituted for the candelilla wax. The same results were obtained whena 50/50 emulsified blend of Jojoba and Carnauba was employed.

The desized and bleach print cloth (Testfabrics' style 400) cited abovewas treated with 1.0 percent blend (50/50 w/w) mixture of oleic andstearic acid at 75 percent wet pickup. After drying, fabric did notignite even after a 4 second flame impingement. The ignition resistanceprotection did not occur after the fabric was laundered to remove theacid blend.

Example 6

The non-flammability and ignition resistance of the bi-regional cottonfibers of the disclosure is determined following the test procedure setforth in 14 C.F.R. §25.853(b). The test is performed as follows:

A minimum of three 1 inch×6 inch×6 inch (2.54 cm×15.24 cm×15.24 cm)specimens (derived from a batting of the bi-regional whole cotton fibersas prepared above. The specimens are conditioned by maintaining them ina conditioning room maintained at a temperature of 70° C.±3° C. and 5percent relative humidity for 24 hours preceding the test.

Each specimen is supported vertically and exposed to a Bunsen or Turillburner with a nominal I.D. tube of 1.5 inches (3.8 cm) in height. Theminimum flame temperature is measured by a calibrated thermocouplepyrometer in the center of the flame and is 1550° F. (843° C.). Thelower edge of the specimen is 0.75 inch (1.91 cm) above the top edge ofthe burner. The flame is applied to the cluster line of the lower edgeof the specimens for 12 seconds and then removed.

Pursuant to the test, the material is self-extinguishing. The averageburn length does not exceed 8 inch (20.32 cm), the average after flamedoes not exceed 15 seconds and flaming drippings did not continue toburn for more than 5 seconds after falling to the burn test cabinetfloor.

Example 7

Ozone has been found to be effective in the de-colorization of dyes suchas indigo (see Wasinger/Hall U.S. Pat. Nos. 5,313,811, 5,366,510 and5,531,796). Ozone is also effective as a bleaching agent on desized andprepared goods in a finishing plant operation (see, Wasinger/Hall U.S.Pat. No. 5,376,143). Ozone may not have been used as a bleaching agenton raw cotton goods because the usual finishing plant preparationprocedures involve the removal of the wax.

Raw cotton yarn can be bleached in a package dyeing machine using ozonewithout removal of the cotton wax to a degree of whiteness ranging from75-85 (AATCC Method 110 “American Association of Textile Chemists andColorists”) depending upon the time, ozone concentration and watertemperature of the treatment. The so bleached goods were found to haveretained almost all of its initial tensile strength along with anincrease in the wet-ability of the goods without any measurable waxremoval. After treatment the package is ready for dyeing.

In a one pound Morton sample package dye machine, is added deionizedwater (pH 6.9-7.2 and 15-18° C.), 0.10 gpl Tergitol wetting agent owbthat was circulate in and out through the yarn package for 5 minutes.Ozone from a ClearWater Tech (Model CD2000P) generator with a dry airflow and at a pressure of 10 psi was added continuously over 30-60minutes depending upon the level of whiteness desired. The flow cyclewas 5 minutes on the outside in and 5 minutes on inside out. Afterrinsing (two in-out cycles) twice with deionized water, the package wasdried by the usual methods. If dyeing is to occur, the packages arealready prepared and do not need to be pre-dried prior to the dyeing.Since the packages are wound in a loose state, normal shrinkage occursand hence the shrinkage in the final garment is mitigated. Anotheradvantage is that small lots can be evaluated for color and otherproperties without the need for long runs to produce enough fabric forfull finishing machinery trials.

Ozone creates hydroxyl (OH⁻) radicals which although they are shortlived at elevated temperatures are sufficiently stabile in cold water toeffectively facilitate in the bleaching along with the ozone itself.

Additional advantages of this bleach system include the absence of BOD(biochemical oxygen demand) in the effluent; any bacteria or fungi inthe cotton goods are also destroyed.

The use of the package machine is also useful for bleaching employingessentially the same low temperature process that is described forfabric bleaching. The advantage of this process is that the yarn is nowready for dyeing without a pre-drying step employed with fabricbleaching.

Other embodiments and uses of the invention will be apparent to thoseskilled in the art from consideration of the specification and practiceof the invention disclosed herein. All references cited herein,including all publications, and all U.S. and foreign patents and patentapplications are specifically and entirely incorporated by reference.The term comprising, where ever used, is intended to include the termsconsisting and consisting essentially of. Furthermore, the termscomprising, including, and containing are not intended to be limiting.It is intended that the specification and examples be consideredexemplary only with the true scope and spirit of the invention indicatedby the following claims.

1. A bi-regional cotton fiber comprised of a cellulosic center and anouter surface comprised of a wax.
 2. The bi-regional fiber of claim 1,wherein the fiber is bleached.
 3. The bi-regional fiber of claim 2,wherein the fiber is bleached with chlorine, ozone, peroxide,hypochlorite or a combination thereof.
 4. The bi-regional fiber of claim1, wherein the wax comprises at least 0.4 percent by weight of saidfiber.
 5. The bi-regional fiber of claim 1, wherein the wax comprisesfrom about 0.4 percent to about 25 percent by weight of said fiber. 6.The bi-regional fiber of claim 1, wherein the wax comprises about 14percent to about 16 percent by weight of said fiber.
 7. The bi-regionalfiber of claim 1, wherein the wax comprises is a natural wax, asynthetic wax, an emulsified wax or a mixture thereof.
 8. Thebi-regional fiber of claim 7, wherein the natural wax is a cotton wax, ajojoba wax, a soy wax, a carnauba wax, or a combination thereof.
 9. Thebi-regional fiber of claim 1, wherein the wax has a melting pointtemperature of about 70° C. or greater.
 10. The bi-regional fiber ofclaim 1, wherein the wax has a melting point temperature of about 90° C.or greater.
 11. The bi-regional fiber of claim 1, which has at least 10percent greater tensile strength as compared to natural cotton fibers.12. The bi-regional fiber of claim 1, which has at least 20 percentgreater tensile strength as compared to natural cotton fibers.
 13. Thebi-regional fiber of claim 1, further comprising applying a saponifiedacid or derivative thereof to the outer surface of the fiber.
 14. Thebi-regional fiber of claim 13, wherein the saponified acid or derivativethereof comprises lauric acid, myristic acid, palmitic acid, stearicacid, oleic acid or combinations thereof.
 15. The bi-regional fiber ofclaim 1, which is fire retardant and/or ignition resistant.
 16. Thebi-regional fiber of claim 15, which meets or exceeds a vertical burntest conducted according to FAR 25.853(b).
 17. The bi-regional fiber ofclaim 1, which contains no harmful chemicals.
 18. The bi-regional fiberof claim 17, wherein the harmful chemicals comprise organohalogens. 19.The bi-regional fiber of claim 1, which has reduced water absorption ascompared to a natural cotton fiber.
 20. A material comprised of aplurality of the bi-regional fibers of claim
 1. 21. The material ofclaim 20, which is fire retardant and/or ignition resistant.
 22. Thematerial of claim 20, which has reduced water absorption as compared toa natural cotton fiber.
 23. The material of claim 20, which has awrinkle resistance greater than conventional cotton.
 24. The material ofclaim 20, further comprising additional fibers.
 25. The material ofclaim 24, wherein the additional fibers comprise natural fibers,synthetic fibers, carbonaceous fibers, and combinations thereof.
 26. Thematerial of claim 24, wherein the synthetic fibers comprise polyester.27. The material of claim 26, wherein the synthetic fibers compriseabout 50 to about 90 percent polyester and about 10 to about 50 percentbi-regional fibers.
 28. The material of claim 25, wherein thecarbonaceous fibers are flexible bi-regional carbonaceous fibers. 29.The material of claim 20, which comprises apparel for infants, toddlers,children or adults.
 30. The material of claim 29, wherein the apparelcomprises shirts, socks, pants, sweaters, sweats, gators, hats, scarves,coats, undergarments, sportswear, skirts, dresses, tops, blankets, anddesigns and combinations thereof.
 31. The material of claim 29, whereinthe apparel is suitable for wear in environments wherein conditions aregreater than and/or less than body temperature.
 32. A method formanufacture of a fiber comprising: bleaching a cotton fiber; andapplying a wax to the fiber.
 33. The method of claim 32, whereinbleaching comprises treating the fiber with chlorine, ozone, peroxide,hypochlorite or a combination thereof.
 34. The method of claim 32,wherein bleaching is performed at about 40° C. or less.
 35. The methodof claim 32, wherein bleaching is performed at room or ambienttemperature.
 36. The method of claim 32, wherein bleaching is performedat a pH of between about 6 and about
 8. 37. The method of claim 32,wherein the fiber comprises ignition resistance without added harmfulchemicals.
 38. The method of claim 32, wherein no wash step is performedafter bleaching and before application of the wax.
 39. The method ofclaim 32, further comprising adding polyester fibers.
 40. The method ofclaim 39, wherein the polyester fibers were treated with a solution of ahydrolyzed partial condensation of trimethoxy methyl silane.